Autoignition-assisted flame regime of sustainable aviation fuel, ammonia and dimethyl ether blends

本项目旨在研究一种新型可持续和环保燃料的燃烧行为，用于能源应用。这些新燃料将有助于减少能源、交通和工业部门的碳排放。新燃料的关键成分之一是氨（NH3），这是一种氢含量高的燃料。虽然氨的储存和运输比氢更安全，但氨的燃烧不同于汽油、柴油和航空燃料等传统化石燃料。因此，本研究项目旨在研究氨和高活性生物质衍生二甲醚（DME）的组合，以复制传统化石燃料的实际燃烧行为。燃烧速度和点火延迟是混合燃料的两个基本特性，在燃烧过程中起着重要的作用。由于这两个特性在设计和开发先进燃烧系统中的重要性，人们对它们进行了广泛的研究。然而，火焰和自燃同时影响燃烧过程的燃烧机制尚不清楚。这种燃烧状态被称为自燃辅助火焰，与传统的层流前提或扩散火焰相比，具有不同的形态和特征。在这种燃烧状态下，火焰在一堆中间物质上传播，这些中间物质是由于混合物的低温化学作用而产生的。本文的研究目的是了解和量化在高温高压下氨和二甲醚混合物的自燃辅助预混合层流火焰。在不同的气体温度，压力，等效比，和Damkӧhler数字的火焰制度将进行实验和数值研究。利用快速压缩机-火焰（RCM-FLAME）装置，结合几种光学诊断技术对火焰状态进行了研究。提出的项目有四个变革方面：(1)在广泛的物理化学条件下火焰传播速度的量化；(2)实验研究第一级和第二级自燃对火焰传播速度的影响；(3)拉伸对向外传播的球形自燃辅助火焰的影响；(4)模拟氨-二甲醚混合物燃烧的动力学模型的准确性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project aims to study the combustion behavior of a new class of sustainable and environmentally friendly fuels for energy applications. Such new fuels will help reduce carbon emissions in the energy, transportation, and industrial sectors. One of the critical components of the new fuel is ammonia (NH3), a fuel with high hydrogen content. While ammonia can be stored and transported more safely than hydrogen, ammonia combustion differs from traditional fossil fuels like gasoline, diesel, and aviation fuels. Therefore, this research project aims to investigate a combination of ammonia and a highly reactive and biomass derived Dimethyl Ether (DME) to replicate the practical combustion behavior of traditional fossil fuels.Flame speed and ignition delay are two fundamental fuel mixture characteristics that play significant roles in the combustion process. Both characteristics have been studied extensively for their importance in designing and developing advanced combustion systems. However, the combustion regime in which the flame and autoignition simultaneously affect the combustion process is not well understood. This combustion regime is called autoignition-assisted flame and has a different morphology and characteristics with respect to traditional laminar premised or diffusion flames. In this combustion regime, the flame propagates over a pool of intermediate species, which are produced due to the low-temperature chemistry of the mixture. The research objective here is to understand and quantify the autoignition-assisted premixed laminar flame of ammonia and DME blends at elevated gas temperatures and pressures. The flame regimes across various gas temperatures, pressures, equivalence ratios, and Damkӧhler numbers will be investigated experimentally and numerically. The Rapid Compression Machine–Flame (RCM-FLAME) apparatus is used to study the flame regime with several optical diagnostic techniques. The proposed project has four transformative aspects: (1) quantification of flame propagation speed over a wide range of physico-chemical conditions, (2) experimental investigation of the effects of first-stage and second-stage autoignition on flame propagation speed, (3) the effect of stretch on outwardly propagating spherical autoignition-assisted flames, and (4) accuracy of kinetic models developed in simulating the combustion of ammonia-DME mixtures.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.